Question

4+8+12+16+20+24+28+32++36+40+44+48+52+56+60+64怎么做

Answer 1

等差数列求和Sₙ＝首项×项数+项数×(项数-1)÷2×等差
将数字带入后得:
4×16+16×(16-1)÷2×4＝544

Answer 2

4+8+12+16+20+24+28+32++36+40+44+48+52+56+60+64
=(4+64)+(8+60）+（12+56）+(16+52)+(20+48)+(24+44)+(28+40)+(32+36)
=68x8
=544